1. Field of the Invention
The present invention relates to continuous passive motion (CPM) devices and, more particularly, to such a device intended for the therapy and rehabilitation of the hand.
2. Description of the Prior Art
Various devices have been contemplated to rehabilitate the hands or the digits thereof through continuous passive motion therapy.
U.S. Pat. No. 1,720,571 issued to Retif on Jul. 9, 1929, discloses an apparatus for exercising the fingers which comprises a flywheel adapted to cause, upon its rotation, a pair of shafts to oscillate. The shafts carry altogether as many collars thereon as there are fingers to exercise. A swivel lever is fixed at a first end thereof by way of a sleeve to each of these collars. The swivel levers are adapted to hold at their second ends the fingers to impart thereto, upon oscillation of the shafts and the collars, various movements in a plane. Various exercises can be obtained depending on the positions of the collars on the shafts.
U.S. Pat. No. 4,368,728, issued to Pasbriq on Jan. 18, 1983, discloses an appliance for training finger joints which includes a plurality of guides mounted in a housing with each of the guides being movable up and down transversely to its longitudinal direction. A plurality of sleeve carriers are slidably mounted on respective ones of the guides. A plurality of finger sleeves extend on top of the housing and are secured to respective ones of the sleeve carriers. A drive is provided for reciprocating the guides up and down with the sleeve carriers and finger sleeves and for reciprocating the sleeve carriers with the finger sleeves along said guides. A horizontal shaft is mounted in the housing for rotation on a first axis. The drive comprises a motor for rotating the shaft. A plurality of eccentric cam wheels are non-rotatably mounted on the shaft. A plurality of levers are pivoted in the housing on a common second axis, which is parallel to the first axis. Each of the levers has a forward end portion, which is spaced from the second axis and constitutes one of the guides and is formed with a longitudinal groove, which receives one of the sleeve carriers. Each the levers rides on the periphery of one of the cam wheels between the groove and the second axis.
"The Journal of Hand Surgery" (pages 474-480, 1979, American Society for Surgery of the Hand) is of interest as disclosing a traction device motor driven through extension flexion for reciprocally and independently driving the digits of a ptient hand along an a curved plastic trolley support. The motor drives a hidden drum, on the periphery which are mounted four rings driven by drive arms mounted directly on the surface of the drum. The rings each have two adjustable tabs that can be moved along the circumference of the ring, the position of these tabs directly relating to the location of trolleys riding on the curved support. Calibration marks assist in locating the tabs in reference to the desired operating range of the trolley which can be each custom set to operate within a determined tolerance range. Similarly, U.S. Pat. No. 4,724,827, issued to Schenck on Feb. 16, 1988, discloses a dynamic traction device for the traction and the flection of an injured area to expedite the healing of bone or soft tissue fractures or other tissues in a patient. For instance, an appendage having a fractured bone is placed in traction and at the same time continuously flexed and extended as is a particular Joint proximally connected to the fractured bone in order to prevent joint tissue deterioration. The portable finger dynamic traction device includes a support structure which is attachable to the body to substantially immobilize joints of the body proximal to the particular joint as is necessary to promote flexing of the proximal joint. Associated with the support structure is an actuator reciprocally movable in a substantially arcuate path which is substantially in the plane of the natural bending movement of the particular joint, distally outward of the fracture and with the particular Joint substantially at the radial center. A tension member tractions the broken appendage to the movable actuator so that the appendage follows the reciprocating movement of the actuator to flex the joint.
U.S. Pat. No. 4,962,756 issued to Shamir et al. on Oct. 16, 1990 and assigned to Danninger Medical Technology, Inc., discloses a portable CPM device which causes controlled continuous passive motion of the digits of a patient's hand. For example, the device when mounted on the dorsal surface of the hand for imparting motion to the four fingers comprises a housing with a motor driven actuating mechanism located therein. The actuating mechanism comprises a reciprocating linear actuation linked to a rotary actuator so that, for therapy of the fingers, the device is rotated about an axis located on the patient's hand that extends transverse to the longitudinal axis of the patient's arm and simultaneously to an actuating arm which is linked to the digits driven back and forth. Linear and rotational elements of actuation are produced, whereby operation of the motor causes the actuating mechanism to drive the digits in a spiral or, more particularly, in a section of a spiral about the axis of rotation, whereby a full palmar closure of the digits in the hand is achieved.
In U.S. Pat. No. 4,679,548 issued on Jul. 14, 1987 to pecheux, the company "Compagnie Generale de Materiel Orthopedique" have also developed a continuous passive motion device which imparts to the fingers a movement resembling that of part of a spiral.
No previous machine provides for the complete motion of all of the joints of the digits, which the present invention achieves through the application of a compound spiral motion to the fingers.